The applicant has proposed converting knit data of a knitted fabric to an image of the knitted fabric to display [the image] on a color monitor or a color printer (Japanese Patent Application No. 2631946). Incidentally, in a knitted fabric in which a plurality of yarns are used, there is a case in which one yarn rolls up another yarn (FIG. 9) and a case in which it does not roll up (FIG. 10). In the case in which a yarn is put round, two sections on the knitted fabric are connected to each other. On the other hand, in the case in which the yarn is not put round, the connection between the two sections is weak, and, for example, a central part between the two sections is independent of the right and left sections as shown in FIG. 10 and thereby can be lifted up or moved to the right or left. However, as far as the applicant knows, the conventional knit design apparatus is not designed to simulate putting round of yarns.